Background and Objective: Although cyclophosphamide is a potent antineoplastic drug its' toxic effects such as damage to the liver, kidney and ovary diminished its widespread utilization. This trial was designed to assess the effect of coenzyme Q10 on cyclophosphamide-induced toxicity in rat liver. Materials and Methods: The rats were divided into 3 groups: In group 1 (control group) (n = 10), nothing was done, group 2 (cyclophosphamide group) (n = 10), 30 mg kg(-1) intraperitoneal cyclophosphamide was administered for 7 days and group 3 (cyclophosphamide+coenzyme Q10 group) (n = 10), 30 mg kg(-1) cyclophosphamide and 10 mg kg(-1) coenzyme Q10 were given for 7 days via intraperitoneal route. Biochemical measurements (SOD and CAT activity and MDA level) were performed. The liver of the rats was surgically extirpated in all groups. Histopathological damage in the liver was evaluated. Results: The hepatocyte damage markers such as inflammation, hemorrhage, necrosis, edema, parenchymal damage and hepatocyte damage were more common in the cyclophosphamide group than cyclophosphamide+coenzyme Q10 group (p<0.05). The activities of SOD and CAT were lower and levels of MDA were higher in the cyclophosphamide group than in the cyclophosphamide+coenzyme Q10 group (p<0.05). Conclusion: Coenzyme Q10 was found to be efficient in preserving the liver tissue from cyclophosphamide-induced toxic effects.